A smart hydrogel and its preparation method and application

Abstract

The present invention relates to the technical field of medical materials, and provides a smart hydrogel, a preparation method thereof, and an application thereof. The present invention introduces dopamine on the surface of TEMPO-oxidized nanocellulose, introduces 3-aminophenylboronic acid on the surface of oxidized dextran, and combines chitosan with polyvinyl alcohol to construct a hydrogel structure with a double cross-linked network based on Schiff base bonds and borate bonds. The present invention utilizes the characteristics of Schiff base bonds and borate bonds to enhance the mechanical properties of the hydrogel system; and due to the reversibility of Schiff base bonds and borate bonds, the smart hydrogel prepared by the present invention exhibits good self-repairing properties, further increasing the service life of the hydrogel; in addition, the smart hydrogel prepared by the present invention exhibits excellent antibacterial properties due to the presence of chitosan, which helps prevent bacterial infection at the wound site, thereby promoting wound repair, and has broad application prospects in the field of wound dressings.

Description

Technical Field

[0001] The present invention relates to the technical field of medical materials, and in particular to a smart hydrogel and a preparation method and application thereof. Background Art

[0002] As an external barrier, the skin performs a vital function, protecting the body from external damage and microbial invasion while maintaining a stable physiological environment. As the largest organ in the human body, the skin is susceptible to damage from surgery, burns, trauma, and chronic diseases, often resulting in tissue defects that significantly impact the quality of life of millions of people worldwide. Tissue engineering has become essential to alleviate the physical and psychological suffering of patients. In clinical practice, wound management requires a material matrix that prevents bacterial infection, inhibits inflammation, and promotes healing. Traditional dressings such as gauze, cotton wool, Band-Aids, bandages, and cotton are commonly used, but they lack bioactivity and the ability to maintain a moist environment, making them only suitable for superficial wounds and requiring frequent changes. Therefore, the development of modern dressings with biocompatibility and moisture retention is crucial to effectively promote healing, improve patient prognosis, and reduce medical costs.

[0003] Hydrogels have a three-dimensional porous structure similar to the extracellular matrix and are rich in water. They have become a popular solution for wound management. In addition to creating a moist environment, absorbing wound exudate and reducing patient discomfort, hydrogel dressings are very suitable for parts of the body that experience significant tensile tension, such as joints and the neck. It is worth mentioning that cellulose nanofibers derived from plant cell walls have been widely studied as biomaterials for tissue engineering due to their nanoscale, richness, tunable surface chemical properties, and biocompatibility, biodegradability, non-toxicity, non-allergy and non-cytotoxicity. However, nanocellulose hydrogels still face challenges in wound healing engineering. The current nanocellulose hydrogels have poor mechanical properties and are difficult to meet the needs of cell growth. In addition, the current nanocellulose hydrogels are generally not self-repairing, have a short service life, and need to be replaced frequently. Summary of the Invention

[0004] In view of this, the present invention provides a smart hydrogel, a preparation method thereof, and an application thereof. The smart hydrogel provided by the present invention has good mechanical properties, self-repairing properties, and good antibacterial properties. When used as a wound dressing, it has excellent wound healing effects and a long service life.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] A smart hydrogel comprising the following raw materials in different mass fractions:

[0007] The invention comprises 1-5% of dopamine-grafted TEMPO-oxidized nanocellulose, 1-6% of 3-aminophenylboronic acid-grafted oxidized dextran, 0.5-2% of chitosan, 0.5-2% of polyvinyl alcohol and the balance of water.

[0008] Preferably, the preparation method of the dopamine-grafted TEMPO-oxidized nanocellulose comprises the following steps:

[0009] The TEMPO-oxidized nanocellulose is mixed with 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride, n-hydroxysuccinimide, dopamine hydrochloride and water to carry out a condensation reaction to obtain the dopamine-grafted TEMPO-oxidized nanocellulose.

[0010] Preferably, the molar ratio of the TEMPO oxidized nanofibers, 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride and n-hydroxysuccinimide is 1:0.2-0.6:0.2-0.6; the molar ratio of the TEMPO oxidized nanofibers to dopamine hydrochloride is 1:0.2-0.8.

[0011] Preferably, the condensation reaction temperature is room temperature and the time is 12 to 24 hours.

[0012] Preferably, the preparation method of the 3-aminophenylboronic acid grafted oxidized dextran comprises the following steps:

[0013] mixing sodium periodate, dextran and water to carry out an oxidation reaction to obtain oxidized dextran;

[0014] The oxidized dextran and 3-aminophenylboronic acid are mixed to carry out a condensation reaction to obtain the oxidized dextran grafted with 3-aminophenylboronic acid.

[0015] Preferably, the molar ratio of sodium periodate to dextran is 1:1-4; the molar ratio of dextran to 3-aminophenylboronic acid is 1-2:1.

[0016] Preferably, the temperature of the oxidation reaction is room temperature, and the reaction time is 6 to 10 hours; the temperature of the condensation reaction is room temperature, and the reaction time is 8 to 14 hours.

[0017] The present invention also provides a method for preparing the smart hydrogel described in the above scheme, comprising the following steps:

[0018] Dopamine-grafted TEMPO-oxidized nanocellulose, 3-aminophenylboronic acid-grafted oxidized dextran, chitosan, polyvinyl alcohol and water are mixed and reacted and cured in sequence to obtain the smart hydrogel.

[0019] Preferably, the reaction temperature is room temperature, and the reaction time is 8 to 24 hours; the curing temperature is room temperature, and the reaction time is 12 to 24 hours.

[0020] The present invention also provides the use of the smart hydrogel described in the above scheme or the smart hydrogel prepared by the preparation method described in the above scheme in the preparation of wound dressings.

[0021] The present invention provides a smart hydrogel comprising the following raw materials by weight: 1-6% dopamine-grafted TEMPO-oxidized nanocellulose, 1-5% 3-aminophenylboronic acid-grafted oxidized dextran, 0.5-2% chitosan, 0.5-2% polyvinyl alcohol, and the balance water. By introducing dopamine onto the surface of the TEMPO-oxidized nanocellulose and 3-aminophenylboronic acid onto the surface of the oxidized dextran, and combining chitosan with polyvinyl alcohol, the hydrogel structure is constructed with a dual cross-linked network based on Schiff base bonds and borate ester bonds. The present invention utilizes the characteristics of Schiff base bonds and borate bonds to enhance the mechanical properties of the hydrogel system; and due to the reversibility of Schiff base bonds and borate bonds, the smart hydrogel provided by the present invention exhibits good self-repairing properties, further increasing the service life of the hydrogel, and providing a new idea for obtaining environmentally friendly, inexpensive and high-performance wound dressing materials with a long service life; in addition, the smart hydrogel prepared by the present invention exhibits excellent antibacterial properties due to the presence of chitosan, which helps prevent bacterial infection at the wound site and promotes wound repair, and has broad application prospects in the field of wound dressings.

[0022] The present invention also provides a method for preparing the smart hydrogel described in the above scheme. This method utilizes a one-pot process to mix dopamine-grafted TEMPO-oxidized nanocellulose, 3-aminophenylboronic acid-grafted oxidized dextran, chitosan, and polyvinyl alcohol, and then reacts and solidifies to produce the smart hydrogel. The reaction process of this method does not require the addition of toxic or hazardous reagents, resulting in simple steps. This promotes green chemistry while also improving production efficiency. Furthermore, the method does not require large-scale equipment during preparation, facilitating subsequent industrial production and enabling further widespread application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the stress-strain curve of the smart hydrogel prepared in Example 6;

[0024] Figure 2 This is a digital photo of the self-repairing process of the smart hydrogel prepared in Example 6;

[0025] Figure 3 This is the stress-strain cycle curve of the smart hydrogel prepared in Example 6;

[0026] Figure 4 The antibacterial effect of the smart hydrogel prepared in Example 6 on Escherichia coli;

[0027] Figure 5The antibacterial effect of the smart hydrogel prepared in Example 6 on Staphylococcus aureus;

[0028] Figure 6 This is the therapeutic effect of the smart hydrogel prepared in Example 6 on wounds in mice. DETAILED DESCRIPTION

[0029] The present invention provides a smart hydrogel, comprising the following raw materials in different mass fractions:

[0030] The invention comprises 1-5% of dopamine-grafted TEMPO-oxidized nanocellulose, 1-6% of 3-aminophenylboronic acid-grafted oxidized dextran, 0.5-2% of chitosan, 0.5-2% of polyvinyl alcohol and the balance of water.

[0031] Unless otherwise specified, all raw materials used in the present invention are commercially available.

[0032] Calculated by mass fraction, the raw materials for preparing the smart hydrogel provided by the present invention include 1-5%, preferably 2-4%, of dopamine-grafted TEMPO-oxidized nanocellulose.

[0033] In the present invention, the preparation method of the dopamine-grafted TEMPO-oxidized nanocellulose preferably includes the following steps: mixing TEMPO (2,2,6,6-tetramethylpiperidine-1-oxide free radical) oxidized nanocellulose with 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride, n-hydroxysuccinimide, dopamine hydrochloride and water to carry out a condensation reaction (referred to as the first condensation reaction) to obtain dopamine-grafted TEMPO-oxidized nanocellulose.

[0034] In the present invention, the molar ratio of the TEMPO oxidized nanofibers, 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride and n-hydroxysuccinimide is preferably 1:0.2~0.6:0.2~0.6, more preferably 1:0.3~0.5:0.3~0.5; the molar ratio of the TEMPO oxidized nanofibers to dopamine hydrochloride is preferably 1:0.2~0.8, more preferably 1:0.3~0.6; and the water is preferably deionized water. In a specific embodiment of the present invention, in the mixed solution obtained by mixing the TEMPO-oxidized nanocellulose with 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride, n-hydroxysuccinimide, dopamine hydrochloride and water, the content of TEMPO-oxidized nanocellulose is preferably 1 wt%, the content of 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride is preferably 2 mg / mL, the content of n-hydroxysuccinimide is preferably 2 mg / mL, and the content of dopamine hydrochloride is preferably 1.5 mg / mL.

[0035] In the present invention, the temperature of the first condensation reaction is preferably room temperature, and the time is preferably 12 to 24 hours, preferably 24 hours; the first condensation reaction is preferably carried out under nitrogen protection conditions; during the first condensation reaction, the amino groups in dopamine and the carboxyl groups in TEMPO-oxidized nanocellulose condense to achieve chemical crosslinking between the dopamine monomer and the TEMPO-oxidized nanocellulose.

[0036] After the first condensation reaction is completed, the present invention preferably centrifuges and washes the resulting product solution to obtain dopamine-grafted TEMPO-oxidized nanocellulose; the rotation speed of the centrifugal washing is preferably 5000-10000 r / min, and the washing time is preferably 10-25 min.

[0037] Calculated by mass fraction, the raw materials for preparing the smart hydrogel provided by the present invention include 1-6% of oxidized dextran grafted with 3-aminophenylboronic acid, preferably 2-5%.

[0038] In the present invention, the preparation method of the 3-aminophenylboronic acid grafted oxidized dextran preferably comprises the following steps:

[0039] mixing sodium periodate, dextran and water to carry out an oxidation reaction to obtain oxidized dextran;

[0040] The oxidized dextran and 3-aminophenylboronic acid are mixed to carry out a condensation reaction to obtain the oxidized dextran grafted with 3-aminophenylboronic acid.

[0041] The present invention comprises mixing sodium periodate, dextran, and water for an oxidation reaction to obtain oxidized dextran. In the present invention, the molar ratio of sodium periodate to dextran is preferably 1:1 to 4, more preferably 1:2 to 3; the weight-average molecular weight of the dextran is preferably 70 to 250 kDA; in the present invention, the water is preferably deionized water; and the dextran to water ratio is preferably 3 mg:1 mL.

[0042] In the present invention, the oxidation reaction temperature is preferably room temperature, the reaction time is preferably 6 to 10 hours, more preferably 8 hours, and the oxidation reaction is preferably carried out under stirring. In a specific embodiment of the present invention, dextran is preferably first added to water to obtain a dextran aqueous solution, and then a sodium periodate aqueous solution is dropwise added to the dextran aqueous solution to carry out the oxidation reaction. The oxidation reaction time is measured from the time when the sodium periodate aqueous solution is completely added. After the oxidation reaction is completed, the resulting product solution can be directly subjected to the next reaction without any further treatment.

[0043] After obtaining the oxidized dextran, the present invention mixes the oxidized dextran with 3-aminophenylboronic acid to undergo a condensation reaction (referred to as the second condensation reaction) to obtain oxidized dextran grafted with 3-aminophenylboronic acid. In the present invention, the molar ratio of the dextran to 3-aminophenylboronic acid is preferably 1 to 2:1. In a specific embodiment of the present invention, 3-aminophenylboronic acid is preferably added directly to the product solution obtained from the oxidation reaction. The ratio of 3-aminophenylboronic acid to deionized water used in the oxidation reaction is preferably 2 mg:1 mL.

[0044] The temperature of the second condensation reaction is preferably room temperature, and the reaction time is preferably 8 to 14 hours, more preferably 12 hours.

[0045] After the second condensation reaction is completed, the present invention preferably dialyzes the resulting product solution to obtain 3-aminophenylboronic acid-grafted oxidized dextran; the molecular weight cutoff of the dialysis bag is preferably 3500-5000 kDa; and the dialysis time is preferably 72 h.

[0046] The raw materials for preparing the smart hydrogel provided by the present invention include chitosan in an amount of 0.5-2%, preferably 1-1.5%, by mass fraction. In the present invention, the weight average molecular weight of the chitosan is preferably 120-250 kDA.

[0047] The raw materials for preparing the smart hydrogel provided by the present invention include 0.5-2% polyvinyl alcohol, preferably 1-1.5% by mass. In the present invention, the weight average molecular weight of the polyvinyl alcohol is preferably 150-250 kDA.

[0048] The raw materials for preparing the smart hydrogel provided by the present invention also include a balance of water, and the water is preferably deionized water.

[0049] The present invention also provides a method for preparing the smart hydrogel described in the above scheme, comprising the following steps:

[0050] Dopamine-grafted TEMPO-oxidized nanocellulose, 3-aminophenylboronic acid-grafted oxidized dextran, chitosan, polyvinyl alcohol and water are mixed and reacted and cured in sequence to obtain a smart hydrogel.

[0051] In the present invention, the reaction temperature is preferably room temperature, and the reaction time is preferably 12 hours; the reaction is preferably carried out under stirring conditions; during the reaction, a borate ester bond is formed between the dopamine-grafted TEMPO-oxidized nanocellulose and the 3-aminophenylboronic acid-grafted oxidized dextran, a borate ester bond is formed between the 3-aminophenylboronic acid-grafted oxidized dextran and polyvinyl alcohol, and a Schiff base reaction occurs between chitosan and the 3-aminophenylboronic acid-grafted oxidized dextran, thereby constructing a hydrogel structure with a double cross-linked network based on Schiff base bonds and borate ester bonds.

[0052] In the present invention, the curing temperature is preferably room temperature, and the curing time is preferably 12 to 24 hours.

[0053] The present invention also provides the use of the smart hydrogel described in the above scheme or the smart hydrogel prepared by the preparation method described in the above scheme in the preparation of wound dressings; the smart hydrogel provided by the present invention has good mechanical properties, self-repairing properties, and good antibacterial properties. It has good therapeutic effects when used as a wound dressing and has a long service life, and has broad application prospects.

[0054] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0055] In the following examples, the weight average molecular weight of the dextran used is 150 kDA, the weight average molecular weight of the chitosan used is 200 kDA, and the weight average molecular weight of the polyvinyl alcohol used is 180 kDA.

[0056] Example 1

[0057] 3 g of TEMPO-oxidized nanocellulose, 0.6 g of 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride, 0.6 g of n-hydroxysuccinimide, 0.45 g of dopamine hydrochloride and 300 mL of deionized water were mixed and stirred at room temperature under nitrogen for 24 hours. During the stirring process, the amino groups in dopamine and the carboxyl groups in TEMPO-oxidized nanocellulose underwent condensation reaction to achieve chemical crosslinking between the dopamine monomer and the TEMPO-oxidized nanocellulose. After the reaction was completed, the obtained reaction solution was washed by high-speed centrifugation at a centrifugal speed of 6000 r / min for 15 minutes to obtain dopamine-grafted TEMPO-oxidized nanocellulose.

[0058] 0.9 g of dextran was added to 300 mL of deionized water to obtain a dextran solution, 0.75 g of sodium periodate was prepared into an aqueous solution, and the sodium periodate aqueous solution was added dropwise to the dextran solution, and the mixture was reacted at room temperature for 8 hours. During the stirring process, the dextran was oxidized to oxidized dextran; after the oxidation reaction was completed, 0.6 g of 3-aminophenylboronic acid was added to the resulting product solution, and the mixture was reacted at room temperature for 12 hours. During the stirring process, 3-aminophenylboronic acid and oxidized dextran underwent a condensation reaction to achieve chemical crosslinking between the two; after the reaction was completed, the resulting product solution was placed in a 3500 kDa dialysis bag and dialyzed for 72 hours to obtain oxidized dextran grafted with 3-aminophenylboronic acid.

[0059] Smart hydrogel was prepared using dopamine-grafted TEMPO-oxidized nanocellulose, 3-aminophenylboronic acid-grafted oxidized dextran, chitosan, polyvinyl alcohol and deionized water. The amount of each raw material used was 1.5% dopamine-grafted TEMPO-oxidized nanocellulose, 5.5% 3-aminophenylboronic acid-grafted oxidized dextran, 1.5% chitosan, 1.5% polyvinyl alcohol, and the balance water, wherein the amount of water used was 100 mL.

[0060] The preparation method of the smart hydrogel is as follows: dopamine-grafted TEMPO-oxidized nanocellulose, 3-aminophenylboronic acid-grafted oxidized dextran, chitosan, and polyvinyl alcohol are mixed in 100 mL of deionized water and reacted at room temperature for 12 hours; during the stirring process, a borate ester bond is formed between the dopamine-grafted TEMPO-oxidized nanocellulose and the 3-aminophenylboronic acid-grafted oxidized dextran, a borate ester bond is formed between the 3-aminophenylboronic acid-grafted oxidized dextran and polyvinyl alcohol, and a Schiff base reaction occurs between chitosan and the 3-aminophenylboronic acid-grafted oxidized dextran; the resulting mixture is cured at room temperature for 12 hours to obtain the smart hydrogel.

[0061] Performance testing:

[0062] (1) Stress / strain performance test: The stress / strain performance of the smart hydrogel was tested using a universal mechanical testing machine according to the ASTM D638 standard. The test specimens were rectangular specimens (specimen length: 125 mm, width: 13 mm, thickness: 0.8 mm), the strain rate was 100 mm / min, and the load was 200 N. The results showed that the elongation at break of the hydrogel was 187%, and the tensile strength was 0.321 MPa.

[0063] (2) Self-recovery performance test: The smart hydrogel prepared in this example was deeply cut into two halves with a scalpel, and then the two halves of the hydrogel were put together. After 5 minutes without the action of external force, the two halves of the hydrogel recovered to their original shape.

[0064] (3) Vibration deformation and recovery cycle test: The self-healing performance of the hydrogel was further evaluated by vibration deformation and recovery cycle test. During the test, the strain and the duration under the corresponding strain were performed as follows: 2.0% (60s) → 100% (60s) → 2.0% (60s) → 100% (60s) → 2.0% (60s) → 100% (60s) → 2.0% (60s) → 100% (60s) → 2.0% (60s) → 100% (60s). The results showed that after 5 cycles, the storage modulus and loss modulus of the hydrogel could almost return to their original values, showing good self-healing and repeatability.

[0065] (3) Antibacterial performance test: The antibacterial effect of the smart hydrogel prepared in this embodiment on Escherichia coli and Staphylococcus aureus was determined according to the standard ASTM E2180. The specific test method is as follows:

[0066] First, Escherichia coli and Staphylococcus aureus were spread on the surface of the agar plate and cultured in a 37°C incubator for 24 hours. 6 A bacterial suspension of 100 CFU / ml and the hydrogel were cultured in a 37°C incubator with constant temperature shaking for 12 hours. After the incubation period, the bacterial suspension was diluted 50-fold and inoculated onto the surface of a solid nutrient culture medium. After constant temperature shaking and incubation for 12 hours in a 37°C incubator, the culture dish was removed, photographed, and counted. Calculations showed that the antibacterial rates of the smart hydrogel prepared in this example against Escherichia coli and Staphylococcus aureus were 88.0% and 91.7%, respectively.

[0067] (4) Wound healing effect test: The wound repair performance of the smart hydrogel prepared in this example was evaluated by constructing a full-thickness skin defect model in mice. The specific method is as follows:

[0068] Male Kunming mice aged 4 to 5 weeks were selected and randomly divided into two groups, including a control group (blank group) and an experimental group. After the mice were raised for 1 week, chloral hydrate was injected into the abdominal cavity of the mice for anesthesia under sterile conditions, and then the skin was prepared. A circular hole with a diameter of nearly 1.5 mm was constructed on the abdomen of the mice using a circular punch. Three parallel samples were set up for each animal experiment. The wounds of the mice in the control group were not treated. The wounds of the experimental group were covered with the prepared hydrogel. The mice were raised in single cages, and the wounds of the mice in the experimental group were photographed to observe the healing of the wounds. The results showed that the wounds of the mice in the control group did not heal after 14 days, while the wounds of the mice in the experimental group healed at 14 days, indicating that the smart hydrogel of the present invention has a good therapeutic effect when used as a wound dressing.

[0069] Example 2

[0070] The other conditions were the same as those in Example 1, except that the amounts of the raw materials used in preparing the smart hydrogel were modified to: 2% dopamine-grafted TEMPO-oxidized nanocellulose, 5% 3-aminophenylboronic acid-grafted oxidized dextran, 1.5% chitosan, 1.5% polyvinyl alcohol, and the remainder water, where the amount of water was 100 mL.

[0071] The obtained smart hydrogel was subjected to stress / strain testing according to the method in Example 1. The results showed that the elongation at break of the hydrogel was 291% and the tensile strength was 0.355 MPa.

[0072] The self-recovery performance of the obtained smart hydrogel was tested according to the method in Example 1. The results showed that the two halves of the hydrogel recovered to their original shape after 4.5 minutes without the action of external force.

[0073] The obtained smart hydrogel was subjected to vibration deformation and recovery cycle tests according to the method in Example 1. The results showed that after 5 cycles, the storage modulus and loss modulus of the hydrogel could almost return to their original values, showing good self-repairability and repeatability.

[0074] The antibacterial performance of the obtained smart hydrogel was tested according to the method in Example 1. The results showed that the antibacterial rates of the smart hydrogel prepared in Example 2 against Escherichia coli and Staphylococcus aureus were 88.3% and 91.1%, respectively.

[0075] The wound treatment effect of the obtained smart hydrogel was tested according to the method in Example 1. The results showed that the wounds of the mice in the control group did not heal after 14 days, while the wounds of the mice in the experimental group healed after 14 days, indicating that it has excellent wound treatment effect.

[0076] Example 3

[0077] The other conditions were the same as those in Example 1, except that the amounts of the raw materials used in preparing the smart hydrogel were modified as follows: 2.5% dopamine-grafted TEMPO-oxidized nanocellulose, 4.5% 3-aminophenylboronic acid-grafted oxidized dextran, 1.5% chitosan, 1.5% polyvinyl alcohol, and the remainder water, wherein the amount of water was 100 mL.

[0078] The obtained smart hydrogel was subjected to stress / strain testing according to the method in Example 1. The results showed that the elongation at break of the hydrogel was 354% and the tensile strength was 0.419 MPa.

[0079] The self-recovery performance of the obtained smart hydrogel was tested according to the method in Example 1. The results showed that the two halves of the hydrogel recovered to their original shape after 4.2 minutes without the action of external force.

[0080] The obtained smart hydrogel was subjected to vibration deformation and recovery cycle tests according to the method in Example 1. The results showed that after 5 cycles, the storage modulus and loss modulus of the hydrogel could almost return to their original values, showing good self-repairability and repeatability.

[0081] The antibacterial performance of the obtained smart hydrogel was tested according to the method in Example 1. The results showed that the antibacterial rates of the smart hydrogel prepared in Example 3 against Escherichia coli and Staphylococcus aureus were 88.5% and 91.5%, respectively.

[0082] The wound treatment effect of the obtained smart hydrogel was tested according to the method in Example 1. The results showed that the wounds of the mice in the control group did not heal after 14 days, while the wounds of the mice in the experimental group healed after 14 days, indicating that it has excellent wound treatment effect.

[0083] Example 4

[0084] The other conditions were the same as those in Example 1, except that the amounts of the raw materials used in preparing the smart hydrogel were modified as follows: 3% dopamine-grafted TEMPO-oxidized nanocellulose, 4% 3-aminophenylboronic acid-grafted oxidized dextran, 1.5% chitosan, 1.5% polyvinyl alcohol, and the remainder water, wherein the amount of water was 100 mL.

[0085] The obtained smart hydrogel was subjected to stress / strain testing according to the method in Example 1. The results showed that the elongation at break of the hydrogel was 401% and the tensile strength was 0.482 MPa.

[0086] The self-recovery performance of the obtained smart hydrogel was tested according to the method in Example 1. The results showed that the two halves of the hydrogel recovered to their original shape after 4.5 minutes without the action of external force.

[0087] The obtained smart hydrogel was subjected to vibration deformation and recovery cycle tests according to the method in Example 1. The results showed that after 5 cycles, the storage modulus and loss modulus of the hydrogel could almost return to their original values, showing good self-repairability and repeatability.

[0088] The antibacterial performance of the obtained smart hydrogel was tested according to the method in Example 1. The results showed that the antibacterial rates of the smart hydrogel prepared in Example 4 against Escherichia coli and Staphylococcus aureus were 88.7% and 91.5%, respectively.

[0089] The wound treatment effect of the obtained smart hydrogel was tested according to the method in Example 1. The results showed that the wounds of the mice in the control group did not heal after 14 days, while the wounds of the mice in the experimental group healed after 14 days, indicating that it has excellent wound treatment effect.

[0090] Example 5

[0091] The other conditions were the same as those in Example 1, except that the amounts of the raw materials used in preparing the smart hydrogel were modified as follows: 3.5% dopamine-grafted TEMPO-oxidized nanocellulose, 3.5% 3-aminophenylboronic acid-grafted oxidized dextran, 1.5% chitosan, 1.5% polyvinyl alcohol, and the remainder water, wherein the amount of water was 100 mL.

[0092] The obtained smart hydrogel was subjected to stress / strain testing according to the method in Example 1. The results showed that the elongation at break of the hydrogel was 483% and the tensile strength was 0.502 MPa.

[0093] The self-recovery performance of the obtained smart hydrogel was tested according to the method in Example 1. The results showed that the two halves of the hydrogel recovered to their original shape after 3.7 minutes without the action of external force.

[0094] The obtained smart hydrogel was subjected to vibration deformation and recovery cycle tests according to the method in Example 1. The results showed that after 5 cycles, the storage modulus and loss modulus of the hydrogel could almost return to their original values, showing good self-repairability and repeatability.

[0095] The antibacterial performance of the obtained smart hydrogel was tested according to the method in Example 1. The results showed that the antibacterial rates of the smart hydrogel prepared in Example 5 against Escherichia coli and Staphylococcus aureus were 88.7% and 91.6%, respectively.

[0096] The wound treatment effect of the obtained smart hydrogel was tested according to the method in Example 1. The results showed that the wounds of the mice in the control group did not heal after 14 days, while the wounds of the mice in the experimental group healed after 14 days, indicating that it has excellent wound treatment effect.

[0097] Example 6

[0098] The other conditions were the same as those in Example 1, except that the amounts of the raw materials used in preparing the smart hydrogel were modified to: 4% dopamine-grafted TEMPO-oxidized nanocellulose, 3% 3-aminophenylboronic acid-grafted oxidized dextran, 1.5% chitosan, 1.5% polyvinyl alcohol, and the remainder water, wherein the amount of water was 100 mL.

[0099] The obtained smart hydrogel was subjected to stress / strain testing according to the method in Example 1, which showed that the elongation at break of the hydrogel was 567% and the tensile strength was 0.521 MPa; Figure 1 This is the stress-strain curve of the smart hydrogel prepared in Example 6.

[0100] The self-recovery performance of the obtained smart hydrogel was tested according to the method in Example 1. The results showed that the two halves of the hydrogel recovered to their original shape after 3 minutes without external force. Figure 2 This is a digital photo of the self-repair process of the smart hydrogel prepared in Example 6.

[0101] The obtained smart hydrogel was subjected to vibration deformation and recovery cycle tests according to the method in Example 1. Figure 3 This is the stress-strain cycle curve of the smart hydrogel prepared in Example 6. Figure 3 It can be seen that the results show that the storage modulus and loss modulus of the hydrogel can almost return to their original values ​​after 5 cycles, showing good self-healing and repeatability.

[0102] The antibacterial performance of the obtained smart hydrogel was tested according to the method in Example 1. The results showed that the antibacterial rates of the smart hydrogel prepared in Example 6 against Escherichia coli and Staphylococcus aureus were 88.8% and 91.8%, respectively. Figure 4The antibacterial effect of the smart hydrogel prepared in Example 6 on Escherichia coli; Figure 5 This is the antibacterial effect of the smart hydrogel prepared in Example 6 on Staphylococcus aureus.

[0103] The wound treatment effect of the obtained smart hydrogel was tested according to the method in Example 1. The results showed that the wounds of the mice in the control group did not heal after 14 days, while the wounds of the mice in the experimental group healed after 14 days, indicating that it has excellent wound treatment effect; Figure 6 This is the therapeutic effect of the smart hydrogel prepared in Example 6 on wounds in mice.

[0104] Example 7

[0105] The other conditions were the same as those in Example 1, except that the amounts of the raw materials used in preparing the smart hydrogel were modified to: 4.5% dopamine-grafted TEMPO-oxidized nanocellulose, 2.5% 3-aminophenylboronic acid-grafted oxidized dextran, 1.5% chitosan, 1.5% polyvinyl alcohol, and the remainder water, wherein the amount of water was 100 mL.

[0106] The obtained smart hydrogel was subjected to stress / strain testing according to the method in Example 1. The results showed that the elongation at break of the hydrogel was 538% and the tensile strength was 0.513 MPa.

[0107] The self-recovery performance of the obtained smart hydrogel was tested according to the method in Example 1. The results showed that the two halves of the hydrogel recovered to their original shape after 3 minutes without the action of external force.

[0108] The obtained smart hydrogel was subjected to vibration deformation and recovery cycle tests according to the method in Example 1. The results showed that after 5 cycles, the storage modulus and loss modulus of the hydrogel could almost return to their original values, showing good self-repairability and repeatability.

[0109] The antibacterial performance of the obtained smart hydrogel was tested according to the method in Example 1. The results showed that the antibacterial rates of the smart hydrogel prepared in Example 7 against Escherichia coli and Staphylococcus aureus were 88.6% and 91.5%, respectively.

[0110] The wound treatment effect of the obtained smart hydrogel was tested according to the method in Example 1. The results showed that the wounds of the mice in the control group did not heal after 14 days, while the wounds of the mice in the experimental group healed after 14 days, indicating that it has excellent wound treatment effect.

[0111] Example 8

[0112] The other conditions were the same as those in Example 1, except that the amounts of the raw materials used in preparing the smart hydrogel were modified as follows: 5% dopamine-grafted TEMPO-oxidized nanocellulose, 2% 3-aminophenylboronic acid-grafted oxidized dextran, 1.5% chitosan, 1.5% polyvinyl alcohol, and the remainder water, wherein the amount of water was 100 mL.

[0113] The obtained smart hydrogel was subjected to stress / strain testing according to the method in Example 1. The results showed that the elongation at break of the hydrogel was 485% and the tensile strength was 0.476 MPa.

[0114] The self-recovery performance of the obtained smart hydrogel was tested according to the method in Example 1. The results showed that the two halves of the hydrogel recovered to their original shape after 3 minutes without the action of external force.

[0115] The obtained smart hydrogel was subjected to vibration deformation and recovery cycle tests according to the method in Example 1. The results showed that after 5 cycles, the storage modulus and loss modulus of the hydrogel could almost return to their original values, showing good self-repairability and repeatability.

[0116] The antibacterial performance of the obtained smart hydrogel was tested according to the method in Example 1. The results showed that the antibacterial rates of the smart hydrogel prepared in Example 8 against Escherichia coli and Staphylococcus aureus were 88.3% and 91.6%, respectively.

[0117] The wound treatment effect of the obtained smart hydrogel was tested according to the method in Example 1. The results showed that the wounds of the mice in the control group did not heal after 14 days, while the wounds of the mice in the experimental group healed after 14 days, indicating that it has excellent wound treatment effect.

[0118] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A smart hydrogel, characterized in that: The preparation comprises the following raw materials by mass fraction: 1-5% dopamine-grafted TEMPO-oxidized nanocellulose, 1-6% 3-aminophenylboronic acid-grafted oxidized dextran, 0.5-2% chitosan, 0.5-2% polyvinyl alcohol, and the balance water; The preparation method of the dopamine-grafted TEMPO-oxidized nanocellulose comprises the following steps: mixing TEMPO-oxidized nanocellulose with 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride, n-hydroxysuccinimide, dopamine hydrochloride and water for a condensation reaction to obtain the dopamine-grafted TEMPO-oxidized nanocellulose; the molar ratio of the TEMPO-oxidized nanocellulose to the dopamine hydrochloride is 1:0.2-0.8; The preparation method of the 3-aminophenylboronic acid grafted oxidized dextran comprises the following steps: mixing sodium periodate, dextran and water for oxidation reaction to obtain oxidized dextran; mixing the oxidized dextran and 3-aminophenylboronic acid for condensation reaction to obtain the 3-aminophenylboronic acid grafted oxidized dextran; the molar ratio of the dextran to the 3-aminophenylboronic acid is 1 to 2:

1.

2. The smart hydrogel according to claim 1, characterized in that The molar ratio of the TEMPO oxidized nanofiber, 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride and n-hydroxysuccinimide is 1:0.2-0.6:0.2-0.

6.

3. The smart hydrogel according to claim 1, characterized in that The condensation reaction temperature is room temperature and the time is 12 to 24 hours.

4. The smart hydrogel according to claim 1, characterized in that The molar ratio of sodium periodate to dextran is 1:1-4.

5. The smart hydrogel according to claim 1, characterized in that The temperature of the oxidation reaction is room temperature, and the reaction time is 6 to 10 hours; the temperature of the condensation reaction is room temperature, and the reaction time is 8 to 14 hours.

6. The method for preparing the smart hydrogel according to any one of claims 1 to 5, characterized in that: The following steps are involved: Dopamine-grafted TEMPO-oxidized nanocellulose, 3-aminophenylboronic acid-grafted oxidized dextran, chitosan, polyvinyl alcohol and water are mixed and reacted and cured in sequence to obtain the smart hydrogel.

7. The preparation method according to claim 6, characterized in that The reaction temperature is room temperature and the reaction time is 8 to 24 hours; the curing temperature is room temperature and the reaction time is 12 to 24 hours.

8. Use of the smart hydrogel according to any one of claims 1 to 5 or the smart hydrogel prepared by the preparation method according to any one of claims 6 to 7 in preparing wound dressings.

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